His younger brother Michael Evans now works with anti-radicalisation charity Families Against Terrorism and Extremism (FATE) to counter the online propaganda that has inspired at least 800 Brits join ISIS, and to prevent other families from enduring the torment of losing a relative to terror.

He told the Standard: “We heard about my brother’s death an hour after he was killed. My mother got a phone call from a freelance reporter asking for a comment, she didn’t even know.

“We never condoned anything he did but we can never get away from the fact that he was out there.

“I think there was two people in him. There was the Thomas I grew up with, the brother I loved and adored, and this person he became, which is Abdul Hakim.

“I always think that although he was shot last year, really my brother died five years ago on the day he left.

“I didn’t want to be dragged into this world but somehow I have become an expert in it. Now I’m not going to let it go to waste.”

The group’s latest project is a music video, filmed in Hackney Wick, east London, featuring acclaimed Moroccan hip-hop star MobyDick.

It aims to educate young people to spot early warning signs of radicalisation and speak out.

Mr Evans, from High Wycombe, Bucks, said: “Any kind of counter-narrative you can get out there is a good thing. The ISIS propaganda is so strong online that we’re playing catch-up to get other views across.

“The more powerful punches you can land the more effective it will be. You want possible converts to be thinking ‘What am I doing? Why am I being an idiot?’

“Being radicalised is similar to being drawn into gang culture. It’s the whole thing of ‘we are your family, we are your brothers, every Muslim is your brother’ - there’s a gang language being spoken.

“You can’t sugarcoat the issue, you need to be direct and get them to look at the devastation they leave behind.

“Their family will lose a loved one, and will be left to live with it for the rest of their lives.”

Rapper MobyDick, who lends the music to the video, said: “I am deeply convinced that culture, art and music brought by a generation of young Arab artists is the best weapon to counter the discourse and actions of Daesh.

“In addition to all the horrors they commit, the terror they sow allows them to distort the image of Arabs worldwide.

“It’s time to fight against hate by highlighting the creative, young and hopeful generation that we all are.”